


Kokoro Kiseki

by toby_is_not_on_fire



Category: Haikyuu!!
Genre: Based on a Vocaloid Song, M/M, Sad, just a lot of tears, they both die, tsukki is a robot, yama is a scientist, yeah - Freeform
Language: English
Status: Completed
Published: 2015-02-25
Updated: 2015-02-25
Packaged: 2018-03-15 05:08:18
Rating: Teen And Up Audiences
Warnings: Major Character Death
Chapters: 1
Words: 2,148
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/3434714
Author URL: https://archiveofourown.org/users/toby_is_not_on_fire/pseuds/toby_is_not_on_fire
Summary: <blockquote class="userstuff">
              <p>Robots can't have hearts. But that's not going to stop Yamaguchi from trying.</p><p>...Or, the sad fic based on Kokoro by Kagamine Rin and Len where Tsukishima is a robot and doesn't have a heart. But Yama still wants him to have one.</p>
            </blockquote>





	Kokoro Kiseki

**Author's Note:**

> tears, robots, trees, and fireflies ahead. you have been warned

He was lonely. His whole life, Yamaguchi Tadashi had been alone. It wasn’t his fault that he was smart and loved to build, to create, to invent. But he was teased from a young age because of it. (That, and the freckles and ahoge he hated.)

So, one day, he took his brain and built something incredible. So lifelike, so realistic, this robot was known as a miracle. The tall bot, with synthetic blond hair, golden sensor-eyes, and incredible artificial intelligence so close to being a personality, was only known to his creator as “Tsukishima” though.

“Tsukki, look at this!” Yamaguchi came running towards the bot, lab coat flying behind, who turned to see his inventor holding a young sapling. As the freckled young man tripped on his shoelaces, Tsukishima was right there to catch him like always.

“You should be careful,” he said monotonously. “You could break your glasses.”

Yamaguchi gave a little laugh from his place in his robot’s arms. “Yeah, but look!” he said, holding up the small plant. “Isn’t it wonderful? We can take care of it and grow it!”

Tsukishima let out a little whirring hum, focusing his sensors on the tiny tree. “Prunus Serrulata,” he identified the cherry tree. “It seems small. It probably won’t live long.”

With a sigh, Yamaguchi stood up on his own. “Tsukki, that’s not the point! The point is it’s a living thing for us to take care of, something that will outlive the both of us and be beautiful!”

Tsukki shrugged mechanically. “Your glasses are falling off. Is there anything else you wish of me?”

“Tsukki…” Yamaguchi sighed. _I want you to learn, to understand. I want you to know what it’s like to be human, to feel happiness and sadness. What it is to love… I want to give you a heart. I want you to be human. That is my wish._

“Nothing right now, thanks!” he said, forcing a smile, faking a laugh. Taking the small tree he walked out a ways into the yard and planted it. What he didn’t see was Tsukishima watching from the window.

“Why does he think such a thing is so important?” the robot wondered. “Why is my involvement necessary to him?”

* * *

 

“Tsukki, are you happy with this life?” Yamaguchi asked one evening as they were sitting in his living room. Tsukki raised a singular computerized eyebrow as he carried the freckled megane his tea.

“What is happy?”

Yamaguchi blinked at the fact that his companion did not at least know what happy was. “Well… It’s when you like what’s going on around you. It makes you want to smile. It’s the opposite of sad. It’s a good feeling!”

The robot paused, considering this for a minute. “What is sad?”

“Oh… It’s when you’re lonely or hurt—hurt emotionally, that is—and you want to cry. It’s painful but it’s part of being human.”

Tsukki thought about this. Happy—to like things and smile? Sad—to cry and be lonely? “…I do not understand. I am sorry.”

Yamaguchi sighed. Could he ever give his only friend a heart, ever make him human? Taking his tea, he stood up. “I’ll be in the lab. I need to work on that program for you, okay?”

The bot hummed. “Don’t take too long; you need sleep. It wouldn’t be good if you fell asleep during tomorrow’s convention.”

He found him two hours later sleeping on the keyboard. Picking him up, he carried the peaceful scientist to his bedroom. placing him on the bed, he turned to leave when he heard Yamaguchi mumble something.

“Sorry Tsukki… Don’t go…”

“I need to charge, you know.” Still, he sat down next to his maker’s futon. _Till he falls asleep._

* * *

 

Yamaguchi let out a sigh. He was sitting on his wheelie chair in the harsh white light of his lab, remembering the past, when he was left alone by everyone. It had been a painful time, everyone mocking him for his genius and looks.

He was brought back to the present with a tap at his shoulder. There, behind him, with a cup of tea and strawberry shortcake, was Tsukishima.

I can see only myself reflected there in your eyes. Why do you live? What does it mean to you? Why do you stay with me?

Flinging his arms around his robot’s neck, he let out a choked sob, not caring that the tea had sloshed over onto him. The robot stood there, uncertain.

Standing back, Yamaguchi let out a sigh and smiled. “Sorry Tsukki! Should we play some volleyball?”

“It makes no difference to me,” the robot said, setting down the cake and turning to go out. “Although it is rather late.”

“Oh that’s alright!” the freckled one said. Reaching for the ball, Yamaguchi opened the door—and stopped in his tracks.

There, lighting up the garden, lawn, and cherry blossom tree, were fireflies of all size and shapes of lights. “Oh…” he said, letting out a breath of air and breaking out in smile. “Could you record this, Tsukki? It’s so beautiful!”

“Alright.” The sensors of Tsukishima’s robotic eyes took in every little detail, recording it to perfection. Knowing what his owner liked best, he paid special attention to the way the lights made the pink cherry blossoms glow with orange tint.

Laughing, Yamaguchi ran out, twirling round and round. And Tsukishima recorded that as well.

* * *

 

Time passed, and Yamaguchi grew and aged. For him, time was not infinite, whereas Tsukki remained as he was, a robot, not human, never aging.

Yamaguchi kept on with his work, trying to find a program that would give his beloved robot a heart. He did his best to explain what he worked for to Tsukishima, but the robot was never able to understand.

* * *

 

He never achieved his goal.

When Yamaguchi died, Tsukishima was unable to feel sad. The house was different though, emptier, and lonely without the awkward and shy scientist to make his life infinitely more interesting. Tsukishima knew that.

The tree Yamaguchi had taken such good care of had grown and covered the lawn in pink snow every spring. It became a giant as the centuries passed, and sometimes people would come to look at it and to meet the miracle robot that had continued on.

He had continued on. After all, he knew how to charge himself, how to oil his own joints, and all such things. He didn’t need to have a human around him to take care of him. He wasn’t lonely. Tsukishima couldn’t be.

Until the warm spring day he wandered out to the cherry tree where his creator and former companion had died. Standing at its base, he reached a hand out and touched its bark. The roughness was familiar by now, as this was something he had done many times over the centuries.

“What is this ‘heart’ thing that he strove for for me? Can I ever understand?” Tsukishima wondered aloud, looking to the red flowers that had grown up at the base of the tree over the years. “I wish… I wish I could.”

He waited a few minutes. But nothing happened. Turning, he headed into the house. And there, across the room, the ancient computer had turned itself on and was glowing yellow-green.

Hesitantly, he reached out. Took his hand back. And then he touched the screen. Instantly, he was met with a new sensation. Pressing his hands to the pounding in his chest, he felt something strange on his face receptors. It was wet.

 _Tears_ , he told himself, awed. But… something was wrong. His newfound heart hurt. Holding his hands out away from him, he saw them tremble. Why? And why were these tears not stopping?

And the new heart kept pounding, accelerating. Was this what he had been searching for?

And he remembered. Not just information in a databank. Real, actual, memory. Everything came rushing back. All the time they had spent together. Grabbing the volleyball, he ran out and let out a powerful spike.

He told me how it feels to be happy!

He remembered.

“It’s when you like what’s going on around you!” Oh, how he loved this sensation known as ‘happy’!

“It makes you want to smile!” And did he ever smile! It felt odd on his face, so used to a frown or an uncaring expression, yet so right!

“It’s a good feeling!” Feeling; feeling anything was incredible! Yes, it was good!

“It’s the opposite of sad!” But there was that too.

He told me how it feels to be sad…

“It’s when you’re lonely or hurt—hurt emotionally, that is.” It did hurt. And he was lonely, he realized. He missed the voice with the frequent “Tsukki!”s and the joyful laugh. He reached into his pocket where his maker’s—his Yamaguchi’s—glasses were kept, where they had been left, safe. He put them on.

“And you want to cry.” He was crying. He didn’t like the sensation of the wet on his cheeks.

“It’s painful but it’s part of being human.” Was this what it took to be human; to have that thing known as ‘heart’? Then he would bear it.

 _Everything is so deep… It’s painful…_ But he was beginning to know, to understand the reason why he was born. It was lonely by oneself.

Looking up, he saw a hole in the tree, standing up, he looked through it easily. There, on the other side was his old and aged Yamaguchi, leaning against the tree like he was when Tsukki had found him, dead with a crown of flowers on his head.

“Yamaguchi!”

* * *

 

Yamaguchi remembered a lot. And his robot, his Tsukki, wasn’t the only incredible thing.

The first miracle, yes, had been the birth of his robot. But there were more.

The second was the time he had been allowed in his life to spend with his miracle robot, friend, and companion.

And the third… He lowered his head with a sigh. The third had not happened yet. The third would be when Tsukishima got his heart.

His bot didn’t understand that yet. “Why do you cry?” had been the words from him when Yamaguchi left the house that morning to walk out to the tree.

But maybe someday…?

Suddenly, he felt a tug at the top of his head. His ahoge was acting up, something it hadn’t done in years. Like it used to, it was pointing. But at what? It used to be a Tsukki antenna, so what was it now?

When he looked up, it felt like all his year faded from in an instant. There, was the inside of a tree, with a hole in it. And in the hole was his robot.

“Yamaguchi!” The first time Tsukki had ever used his name.

Something was pulling him through the hole, and he didn’t fight it. When he looked back, he saw is old form, and when he looked down, he was fifteen again. But all he looked at was his robot, now crying, now human.

“I have something to tell you!” Tsukki called, and he was wearing Yamaguchi’s glasses. “From the future!”

And Yamaguchi had knocked him to the ground, and they were smiling, and it was happy. And when Tsukki came out of his daze, he looked over. And there was Yamaguchi, freckles and all, right there in front of him.

Smile changed to a smirk and he leapt over and began to tickle Yamaguchi. The inventor, the scientist, the maker, the friend curled up, laughing so hard as he tried to defend himself.

The third miracle was that Tsukki now had his heart. And a fourth? A fourth wasn’t needed.

And then Tsukki stopped and smiled at him. Yamaguchi, let up, saw the flowers surrounding and, with a soft “Oh!” began to weave them together, making a crown for each of them.

They spent their day playing, Yamaguchi discovering that his robot was actually a tsundere, Tsukki discovering just how fun volleyball could be, and both of them overwhelmingly happy.

When the evening came, they sat against the giant tree. Talked, and laughed, and held hands. And all around them were fireflies.

“Remember?” Yamaguchi said. He didn’t need any more words, because Tsukki did. “Kei… Your name is Tsukishima Kei. Is that okay?”

“…Yeah,” Tsukki said, looking at the little golden-orange lights. “…It is.”

* * *

 

When Tsukki woke up, Yamaguchi was gone. His life had ended. He left his beloved robot that was human alone.

But.

He also gave him the key to the miracle that had made both so happy.

The miracle only lasted a moment though.

You see... the heart was far too big for the robot called Tsukki.

Unable to withstand the weight, Tsukishima Kei shorted out and was never to move again.

But on his face was a beautiful, real smile.

He looked like an angel.

**Author's Note:**

> WELL DID YOU CRY??? i did. r.i.p. toby  
> also you can't tell me yamadoodle's ahoge is not a tsukki antenna. because it is
> 
> please donate your tears to me as that is what i live on and please donate your spare hugs to the tsukki and yama need a hug foundation.  
> this has been a message from our sponsors.  
> thank you


End file.
